U.S. patent application number 16/040669 was filed with the patent office on 2019-02-28 for thermal recovery methods for recovering viscous hydrocarbons from a subterranean formation.
The applicant listed for this patent is Sriram Doraiswamy, Robert D. Kaminsky, Rahman Khaledi. Invention is credited to Sriram Doraiswamy, Robert D. Kaminsky, Rahman Khaledi.
Application Number | 20190063199 16/040669 |
Document ID | / |
Family ID | 60190993 |
Filed Date | 2019-02-28 |
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United States Patent
Application |
20190063199 |
Kind Code |
A1 |
Doraiswamy; Sriram ; et
al. |
February 28, 2019 |
THERMAL RECOVERY METHODS FOR RECOVERING VISCOUS HYDROCARBONS FROM A
SUBTERRANEAN FORMATION
Abstract
Thermal recovery methods for recovering viscous hydrocarbons
from a subterranean formation. The thermal recovery methods include
performing a plurality of injection cycles. Each injection cycle in
the plurality of injection cycles includes injecting a heated
solvent vapor stream into a heated chamber that extends within the
subterranean formation and fluidly contacting the viscous
hydrocarbons with the heated solvent vapor stream to generate
mobilized viscous hydrocarbons. Each injection cycle also includes
injecting a steam stream into the heated chamber. The thermal
recovery methods further include producing a chamber liquid and/or
mobilized viscous hydrocarbons from the subterranean formation.
Inventors: |
Doraiswamy; Sriram; (Spring,
TX) ; Khaledi; Rahman; (Calgary, CA) ;
Kaminsky; Robert D.; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Doraiswamy; Sriram
Khaledi; Rahman
Kaminsky; Robert D. |
Spring
Calgary
Houston |
TX
TX |
US
CA
US |
|
|
Family ID: |
60190993 |
Appl. No.: |
16/040669 |
Filed: |
July 20, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/2408 20130101;
C09K 8/592 20130101; E21B 43/24 20130101 |
International
Class: |
E21B 43/24 20060101
E21B043/24; C09K 8/592 20060101 C09K008/592 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2017 |
CA |
2978157 |
Claims
1. A method for recovering viscous hydrocarbons from a subterranean
formation, the method comprising: a plurality of injection cycles,
wherein each injection cycle in the plurality of injection cycles
includes: (i) injecting, via an at least substantially horizontal
region of an injection well and for a heated solvent vapor
injection time period, a heated solvent vapor stream into a heated
chamber that extends within the subterranean formation, wherein the
heated solvent vapor stream includes at least 50 weight percent
nonaqueous species; (ii) fluidly contacting the viscous
hydrocarbons with the heated solvent vapor stream to generate
mobilized viscous hydrocarbons within the heated chamber; and (iii)
subsequent to the heated solvent vapor injection time period and
for a steam injection time period, injecting, via the at least
substantially horizontal region of the injection well, a steam
stream into the heated chamber; and during at least one injection
cycle of the plurality of injection cycles, producing the mobilized
viscous hydrocarbons from the subterranean formation via an at
least substantially horizontal region of a production well that
extends within the heated chamber and below the at least
substantially horizontal region of the injection well.
2. The method of claim 1, wherein the subterranean formation
includes subterranean strata, which extend within the heated
chamber, wherein the method further includes condensing the heated
solvent vapor stream on the subterranean strata to generate
condensed solvent, and further wherein the injecting the steam
stream includes vaporizing the condensed solvent to generate
vaporized solvent.
3. The method of claim 2, wherein the subterranean formation
includes an interface region, which extends between the heated
chamber and a remainder of the subterranean formation, and further
wherein the injecting the steam stream includes at least one of:
facilitating flow of the heated solvent vapor stream into fluid
contact with the interface region; and (ii) facilitating flow of
a/the vaporized solvent into fluid contact with the interface
region.
4. The method of claim 3, wherein the injecting the steam stream
includes flushing condensed solvent from the heated chamber, and
the flushing includes facilitating flow of the condensed solvent
from the subterranean formation via the production well.
5. The method of claim 4, wherein the flushing includes
facilitating condensation of the heated solvent vapor stream within
an/the interface region that extends between the heated chamber and
a remainder of the subterranean formation.
6. The method of claim 5, wherein the method defines an injection
time ratio of the heated solvent vapor injection time period to the
steam injection time period.
7. The method of claim 5, wherein the injection time ratio is
selected to prevent fluid contact between the steam stream and
an/the interface region that extends between the heated chamber and
a remainder of the subterranean formation.
8. The method of claim 5, wherein, responsive to an increase in a
volume of the heated chamber, the method further includes
increasing the injection time ratio in a given injection cycle of
the plurality of injection cycles relative to a prior injection
cycle of the plurality of injection cycles.
9. The method of claim 5, wherein the method further includes
modifying the injection time ratio for a/the given injection cycle
of the plurality of injection cycles relative to a/the prior
injection cycle of the plurality of injection cycles based, at
least in part, on at least one of: a change in a production rate of
mobilized viscous hydrocarbons; (ii) the production rate of
mobilized viscous hydrocarbons; (iii) a change in a concentration
of solvent in the mobilized viscous hydrocarbons produced from the
subterranean formation; (iv) the concentration of solvent in the
mobilized viscous hydrocarbons produced from the subterranean
formation; (v) a change in a production temperature of the
mobilized viscous hydrocarbons; (vi) the production temperature of
the mobilized viscous hydrocarbons; and (vii) a temperature within
the heated chamber.
10. The method of claim 5, wherein the method further includes
transitioning from the injecting the heated solvent vapor stream to
the injecting the steam stream based, at least in part, on at least
one of: (i) a/the change in a production rate of mobilized viscous
hydrocarbons; (ii) the production rate of mobilized viscous
hydrocarbons; (iii) a/the change in a concentration of solvent in
the mobilized viscous hydrocarbons produced from the subterranean
formation; (iv) the concentration of solvent in the mobilized
viscous hydrocarbons produced from the subterranean formation; (v)
a/the change in a/the production temperature of the mobilized
viscous hydrocarbons; (vi) the production temperature of the
mobilized viscous hydrocarbons; and (vii) a/the temperature within
the heated chamber.
11. The method of claim 5, wherein the injecting the heated solvent
vapor stream includes injecting a mass of heated solvent vapor, and
further wherein the injecting the steam stream includes injecting a
mass of steam.
12. The method of claim 11, wherein, during each injection cycle of
the plurality of injection cycles, an injection mass ratio of the
mass of heated solvent vapor to the mass of steam is one of: (i) at
least 1.0; (ii) at least 1.25; (iii) at least 1.5; (iv) at least
2.0; (v) at least 3; (vi) at least 4; (vii) at least 6; (viii) at
least 8; (ix) at least 10; (x) at least 12.5; (xi) at least 15;
(xii) at least 20; (xiii) at least 25; and (xiv) at least 30.
13. The method of claim 5, wherein the method further includes
maintaining a target operating pressure within the heated chamber
by the injecting the heated solvent vapor stream and the injecting
the steam stream at the target operating pressure.
14. The method of claim 13, wherein the maintaining includes
selectively varying at least one of a temperature of the heated
solvent vapor stream and a temperature of the steam stream to
maintain the target operating pressure.
15. The method of claim 1, wherein the fluidly contacting includes
condensing the heated solvent vapor stream to form a chamber liquid
that includes condensed solvent and the mobilized viscous
hydrocarbons, wherein the producing includes producing at least a
portion of the chamber liquid as a produced chamber liquid, and
further wherein: (i) prior to the injecting the steam stream, the
method includes accumulating the chamber liquid within the heated
chamber to form a chamber liquid pool within the heated chamber and
immersing the at least substantially horizontal region of the
injection well within the chamber liquid pool; and (ii) initiating
the injecting the steam stream subsequent to the at least
substantially horizontal region of the injection well being
immersed within the chamber liquid pool.
16. The method of claim 15, wherein the accumulating includes
accumulating such that the at least substantially horizontal region
of the injection well is completely immersed within the chamber
liquid pool.
17. The method of claim 16, wherein the accumulating includes
accumulating such that the at least substantially horizontal region
of the injection well is a threshold distance below an upper
surface of the chamber liquid pool, wherein the threshold distance
is at least one of: at least 0.5 meters; (ii) at least 1 meter;
(iii) at least 2 meters; (iv) at least 3 meters; (v) at least 4
meters; (vi) at most 8 meters; (vii) at most 6 meters; and (viii)
at most 4 meters.
18. The method of claim 15, wherein the accumulating includes
regulating a production rate of the produced chamber liquid to
increase a volume of the chamber liquid within the heated
chamber.
19. The method of claim 18, wherein the regulating includes at
least one of: (i) increasing the production rate of the produced
chamber liquid responsive to an/the upper surface of the chamber
liquid pool being above the at least substantially horizontal
region of the injection well; (ii) increasing the production rate
of the produced chamber liquid responsive to the upper surface of
the chamber liquid pool being greater than a/the threshold distance
above the at least substantially horizontal region of the injection
well; and (iii) decreasing the production rate of the produced
chamber liquid responsive to the upper surface of the chamber
liquid pool being below the at least substantially horizontal
region of the injection well.
20. The method of claim 15, wherein the method further includes
monitoring a composition variable associated with a solvent content
of the produced chamber liquid, wherein the method further includes
at least one of: (i) selectively regulating an injection rate of
the heated solvent vapor stream based, at least in part, on the
composition variable; and (ii) selectively regulating an injection
rate of the steam stream based, at least in part, on the
composition variable; and the monitoring the composition variable
includes at least one of: (i) monitoring a density of the produced
chamber liquid; (ii) monitoring a viscosity of the produced chamber
liquid; and (iii) monitoring a chemical composition of the produced
chamber liquid.
21. The method of claim 20, wherein the method further includes
monitoring a liquid level variable associated with a location of
an/the upper surface of the chamber liquid pool within the heated
chamber, and further wherein the accumulating is based, at least in
part, on the liquid level variable; and the monitoring the liquid
level variable includes at least one of: (i) monitoring at least
one pressure within the heated chamber; (ii) monitoring a
differential pressure between two different depths within the
heated chamber; (iii) monitoring at least one temperature within
the heated chamber and comparing the at least one temperature to an
estimated bubble point temperature of the chamber liquid; (iv)
monitoring a temperature differential within the heated chamber;
(v) monitoring a change in a production temperature of the
mobilized viscous hydrocarbons; (vi) monitoring the production
temperature of the mobilized viscous hydrocarbons; and (vii)
monitoring a water-to-hydrocarbon ratio within the produced chamber
liquid.
22. The method of claim 5, wherein the heated solvent vapor stream
includes a near-azeotropic mixture of a hydrocarbon solvent and
water; wherein a solvent molar fraction of the hydrocarbon solvent
in the near-azeotropic mixture is 70%-130% of an azeotropic solvent
molar fraction of the near-azeotropic mixture at a target operating
pressure within the heated chamber.
23. The method of claim 22, wherein a bubble point temperature of
the heated solvent vapor stream at a/the target operating pressure
within the heated chamber is less than a bubble point temperature
of the steam stream at the target operating pressure within the
heated chamber.
24. A method for recovering viscous hydrocarbons from a
subterranean formation, the method comprising: injecting, via an at
least substantially horizontal region of an injection well, a
heated solvent vapor stream into a heated chamber that extends
within the subterranean formation; fluidly contacting the viscous
hydrocarbons with the heated solvent vapor stream and condensing
the heated solvent vapor stream to generate mobilized viscous
hydrocarbons within the heated chamber and to form a chamber liquid
that includes condensed solvent and the mobilized viscous
hydrocarbons; accumulating the chamber liquid to form a chamber
liquid pool within the heated chamber and to immerse the at least
substantially horizontal region of the injection well within the
chamber liquid pool; subsequent to the accumulating, injecting, via
the at least substantially horizontal region of the injection well,
a steam stream into the heated chamber such that the steam stream
directly contacts at least a region of the chamber liquid pool and
vaporizes a fraction of the chamber liquid from the chamber liquid
pool; during at least one of the injecting the heated solvent vapor
stream, the fluidly contacting, and the injecting the steam stream,
producing at least a portion of the chamber liquid, as a produced
chamber liquid, from the subterranean formation via an at least
substantially horizontal region of a production well that extends
within the heated chamber and below the at least substantially
horizontal region of the injection well; and sequentially
repeating, for a plurality of injection cycles, the injecting the
heated solvent vapor steam, the fluidly contacting, the injecting
the steam stream, and the producing.
25. The method of claim 24, wherein the sequentially repeating, for
a plurality of injection cycles, includes the accumulating.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Canadian Patent
Application 2,978,157 filed 31 Aug. 2017 entitled THERMAL RECOVERY
METHODS FOR RECOVERING VISCOUS HYDROCARBONS FROM A SUBTERRANEAN
FORMATION, the entirety of which is incorporated by reference
herein.
FIELD OF THE DISCLOSURE
[0002] The present disclosure is directed generally to thermal
recovery methods of recovering viscous hydrocarbons from a
subterranean formation and more particularly to thermal recovery
methods that sequentially inject a heated solvent vapor stream and
a steam stream into the subterranean formation.
BACKGROUND OF THE DISCLOSURE
[0003] Hydrocarbons often are utilized as fuels and/or as chemical
feedstocks for manufacturing industries. Hydrocarbons naturally may
be present within subterranean formations, which also may be
referred to herein as reservoirs and/or as hydrocarbon reservoirs.
Such hydrocarbons may occur in a variety of forms, which broadly
may be categorized herein as conventional hydrocarbons and
unconventional hydrocarbons. A process utilized to remove a given
hydrocarbon from a corresponding subterranean formation may be
selected based upon one or more properties of the hydrocarbon
and/or of the subterranean formation.
[0004] Examples of hydrocarbon production techniques that may be
utilized to produce viscous hydrocarbons from a subterranean
formation include thermal recovery processes. Thermal recovery
processes generally inject a thermal recovery stream, at an
elevated temperature, into the subterranean formation. The thermal
recovery stream contacts the viscous hydrocarbons, within the
subterranean formation, and heats, dissolves, and/or dilutes the
viscous hydrocarbons, thereby generating mobilized viscous
hydrocarbons. The mobilized viscous hydrocarbons generally have a
lower viscosity than a viscosity of the naturally occurring viscous
hydrocarbons at the native temperature and pressure of the
subterranean formation and may be pumped and/or flowed from the
subterranean formation. A variety of different thermal recovery
processes have been utilized, including cyclic steam stimulation
processes, solvent-assisted cyclic steam stimulation processes,
steam flooding processes, solvent-assisted steam flooding
processes, steam-assisted gravity drainage processes,
solvent-assisted steam-assisted gravity drainage processes, heated
vapor extraction processes, liquid addition to steam to enhance
recovery processes, and/or near-azeotropic gravity drainage
processes.
[0005] Thermal recovery processes may differ in the mode of
operation and/or in the composition of the thermal recovery stream.
However, all thermal recovery processes rely on injection of the
thermal recovery stream into the subterranean formation, at the
elevated temperature, and thermal contact between the thermal
recovery stream and the subterranean formation heats the
subterranean formation.
[0006] In thermal recovery processes, such as heated vapor
extraction, that utilize a solvent, or a hydrocarbon solvent, as
the thermal recovery stream, solvent loss to the subterranean
formation may increase production costs and/or limit production
economies. As an example, a decrease in an amount of solvent needed
to produce viscous hydrocarbons from the subterranean formation may
cause a corresponding decrease in production costs as long as the
savings associated with the decrease in solvent utilization is not
offset by a corresponding increase in energy consumption.
[0007] In addition, recovered solvent generally is separated from
the viscous hydrocarbons and re-injected into the subterranean
formation, and increases in a volume of the solvent recycled also
may increase production costs and/or limit production economies. As
another example, a decrease in the volume of solvent produced from
the subterranean formation may permit a corresponding decrease in
surface facility size required for solvent separation, recovery,
and re-injection, also decreasing production costs.
[0008] Historically, thermal recovery processes may utilize solvent
inefficiently within the subterranean formation, leading to
increased solvent loss to the subterranean formation and/or
increased production of solvent from the subterranean formation.
Thus, there exists a need for improved thermal recovery methods for
recovering viscous hydrocarbons from a subterranean formation.
SUMMARY OF THE DISCLOSURE
[0009] Thermal recovery methods for recovering viscous hydrocarbons
from a subterranean formation. The thermal recovery methods include
performing a plurality of injection cycles. Each injection cycle in
the plurality of injection cycles includes injecting a heated
solvent vapor stream into a heated chamber that extends within the
subterranean formation. The heated solvent vapor stream is injected
via an at least substantially horizontal region of an injection
well that extends within the heated chamber and for a heated
solvent vapor injection time period. Each injection cycle also
includes fluidly contacting the viscous hydrocarbons with the
heated solvent vapor stream to generate a chamber liquid and/or
mobilized viscous hydrocarbons. Each injection cycle further
includes injecting a steam stream into the heated chamber. The
steam stream is injected via the at least substantially horizontal
region of the injection well and for a steam injection time period.
The thermal recovery methods further include producing the chamber
liquid and/or the mobilized viscous hydrocarbons from the
subterranean formation. The producing may be performed during at
least one injection cycle of the plurality of injection cycles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic representation of examples of a
hydrocarbon production system that may be utilized with methods
according to the present disclosure.
[0011] FIG. 2 is a plot illustrating recovery factor as a function
of time for eight different injection strategies.
[0012] FIG. 3 is a plot illustrating cumulative solvent-to-oil
ratio as a function of recovery factor for the injection strategies
of FIG. 2.
[0013] FIG. 4 is a flowchart depicting methods, according to the
present disclosure, for recovering viscous hydrocarbons from a
subterranean formation.
[0014] FIG. 5 is a schematic transverse cross-sectional view of a
heated chamber illustrating a portion of the method of FIG. 4.
[0015] FIG. 6 is a schematic transverse cross-sectional view of a
heated chamber illustrating a portion of the method of FIG. 4.
[0016] FIG. 7 is a schematic transverse cross-sectional view of a
heated chamber illustrating a portion of the method of FIG. 4.
[0017] FIG. 8 is a schematic transverse cross-sectional view of a
heated chamber illustrating a portion of the method of FIG. 4.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0018] FIGS. 1-8 provide examples of hydrocarbon production systems
10, of portions of hydrocarbon production systems 10, and/or of
methods 100, according to the present disclosure. Elements that
serve a similar, or at least substantially similar, purpose are
labeled with like numbers in each of FIGS. 1-8, and these elements
may not be discussed in detail herein with reference to each of
FIGS. 1-8. Similarly, all elements may not be labeled in each of
FIGS. 1-8, but reference numerals associated therewith may be
utilized herein for consistency. Elements, components, and/or
features that are discussed herein with reference to one or more of
FIGS. 1-8 may be included in and/or utilized with any of FIGS. 1-8
without departing from the scope of the present disclosure. In
general, elements that are likely to be included in a particular
embodiment are illustrated in solid lines, while elements that are
optional are illustrated in dashed lines. However, elements that
are shown in solid lines may not be essential and, in some
embodiments, may be omitted without departing from the scope of the
present disclosure.
[0019] FIG. 1 is a schematic representation of examples of a
hydrocarbon production system 10 that may be utilized with methods
100, according to the present disclosure. As illustrated in FIG. 1,
hydrocarbon production system 10 includes an injection well 30 and
a production well 40.
[0020] Injection well 30 and production well 40 extend within a
subterranean formation 24 that includes viscous hydrocarbons 26.
Injection well 30 and production well 40 also may extend, or may be
referred to herein as extending, between a surface region 20 and
subterranean formation 24 and/or within a subsurface region 22.
[0021] Injection well 30 includes an injection wellhead 32 and an
injection wellbore 34. Similarly, production well 40 includes a
production wellhead 42 and a production wellbore 44.
[0022] During operation of hydrocarbon production system 10,
injection well 30 may be utilized to provide, to supply, and/or to
inject an injectant stream 60 into subterranean formation 24.
Injectant stream 60 may include a heated solvent vapor stream 62
and/or a steam stream 64. Injectant stream 60 may interact with,
contact, physically contact, fluidly contact, mix with, and/or heat
viscous hydrocarbons 26, within subterranean formation 24, thereby
producing, generating, and/or forming mobilized viscous
hydrocarbons 72 within the subterranean formation. The mobilized
viscous hydrocarbons may form a portion of a chamber liquid 70,
which also may include a condensed fraction of injectant stream 60,
such as a condensed fraction of the heated solvent vapor stream
and/or a condensed fraction of the steam stream. Chamber liquid 70,
including mobilized viscous hydrocarbons 72, may flow, under the
influence of gravity, to production well 40, which may produce the
chamber liquid and/or the mobilized viscous hydrocarbons from the
subterranean formation.
[0023] Injection of injectant stream 60 into the subterranean
formation and production of chamber liquid 70 from the subterranean
formation may produce and/or generate a heated chamber 50 within
the subterranean formation. The heated chamber may grow, with time,
such as may be responsive to continued injection of the injectant
stream and/or continued production of the chamber liquid. Heated
chamber 50 and subterranean formation 24 may form and/or define an
interface region 52 therebetween.
[0024] As schematically illustrated in dashed lines in FIG. 1,
hydrocarbon production system 10 may include one or more sensors
80. Sensors 80, when present, may be adapted, configured, designed,
constructed, and/or programmed to monitor and/or determine any
suitable property of hydrocarbon production system 10, including
subterranean formation 24, heated chamber 50, and/or chamber liquid
70. As an example, sensors 80 may be configured to monitor a
composition variable of chamber liquid 70. The composition variable
may indicate a solvent content, a water content, a viscous
hydrocarbon content, and/or a mobilized viscous hydrocarbon content
of chamber liquid 70 that is produced via production well 40. As
additional examples, sensors 80 may be configured to monitor any
suitable temperature, pressure, chemical composition, chemical
property, and/or physical property of any suitable portion of
hydrocarbon production system 10 and/or of streams that may flow
within the hydrocarbon production system. Additional examples of
variables that may be monitored by sensors 80 are disclosed
herein.
[0025] As also schematically illustrated in dashed lines in FIG. 1,
hydrocarbon production system 10 may include surface facilities 90.
Surface facilities 90 also may be referred to herein as separation
facilities 90 and may be adapted, configured, designed, and/or
constructed to receive chamber liquid 70 that is produced from
subterranean formation 24 and to separate the received chamber
liquid into a produced hydrocarbon stream 92 and injectant stream
60. As such, the presence of surface facilities 90 may facilitate
recycling, or re-injection, of the portion of the injectant stream
that is produced from the subterranean formation with the produced
chamber liquid.
[0026] As discussed in more detail herein with reference to methods
100 of FIG. 4, hydrocarbon production system 10 may be utilized to
perform a plurality of injection cycles. In each injection cycle, a
heated solvent vapor stream initially may be injected into the
subterranean formation. The heated solvent vapor stream may fluidly
contact viscous hydrocarbons within the subterranean formation,
thereby generating mobilized viscous hydrocarbons. Subsequent to
injection of the heated solvent vapor stream for a heated solvent
vapor injection time period, a steam stream may be injected into
the subterranean formation for a stream injection time period.
[0027] The steam stream generally will have a higher temperature,
and a higher concentration of thermal energy, when compared to the
corresponding properties of the heated solvent vapor stream. Stated
another way, a steam temperature, at which the steam stream has a
given vapor pressure, may be greater than a solvent vapor
temperature, at which the heated solvent vapor stream has the same
given vapor pressure. In addition, a heat capacity and/or a heat of
vaporization of the steam stream may be greater than a heat
capacity and/or a heat of vaporization of the heated solvent vapor
stream. As such, injection of the steam stream into subterranean
formation 24 and/or into heated chamber 50 may vaporize condensed
solvent that comes into contact with the steam stream.
[0028] This vaporization of condensed solvent may provide several
benefits over thermal recovery processes that inject the heated
solvent vapor stream but that do not subsequently, and cyclically,
inject the steam stream. As an example, vaporization of the
condensed solvent within the heated chamber, thereby re-forming the
heated solvent vapor stream within the heated chamber, may improve
and/or increase supply of the heated solvent vapor stream to
interface region 52. This may improve the efficiency of solvent
utilization within the subterranean formation and/or may decrease a
volume of condensed solvent produced from the subterranean
formation and provided to surface facilities 90. As another
example, vaporization of the condensed solvent within the heated
chamber may decrease a potential for loss of the condensed solvent
within the heated chamber by providing a driving force for
production of the condensed solvent from the subterranean formation
via production well 40.
[0029] With the above in mind, FIG. 2 is a plot illustrating a
recovery factor as a function of time for eight different injection
strategies. As indicated as "Base" in FIG. 2, these injection
strategies include a base, baseline, and/or control condition, in
which the heated solvent vapor stream continuously is injected into
the subterranean formation. The illustrated injection strategies
further include seven experimental conditions in which heated
solvent vapor and steam are sequentially injected for various
relative timeframes. The recovery factor refers to a cumulative
production of viscous hydrocarbons from the subterranean formation,
and all plots are normalized to the base condition. A higher
recovery factor generally is considered to indicate improved
recovery of viscous hydrocarbons from the subterranean formation
relative to a lower recovery factor. The experimental conditions
include: [0030] 1) a 30.30 condition, in which each injection cycle
includes 30 days of heated solvent vapor injection followed by 30
days of steam injection; [0031] 2) a 1.1 condition, in which each
injection cycle includes 1 day of heated solvent vapor injection
followed by 1 day of steam injection; [0032] 3) a 30.3 condition,
in which each injection cycle includes 30 days of heated solvent
vapor injection followed by 3 days of steam injection; [0033] 4) a
10.1 condition, in which each injection cycle includes 10 days of
heated solvent vapor injection followed by 1 day of steam
injection; [0034] 5) a 30.2 condition, in which each injection
cycle includes 30 days of heated solvent vapor injection followed
by 2 days of steam injection; [0035] 6) a 15.1 condition, in which
each injection cycle includes 15 days of heated solvent vapor
injection followed by 1 day of steam injection; and [0036] 7) a
30.1 condition, in which each injection cycle includes 30 days of
heated solvent vapor injection followed by 1 day of steam
injection.
[0037] As may be seen from FIG. 2, injection strategies that inject
the heated solvent vapor stream and the steam stream for comparable
time periods (e.g., the 30.30 and 1.1 conditions) exhibit a
decrease in the recovery factor as a function of time when compared
to injection strategies that inject the heated solvent vapor stream
for a significantly longer amount of time when compared to the
steam stream (e.g., the 30.3, 10.1, 30.2, 15.1, and 30.1
conditions). In general, viscous hydrocarbons may be converted more
effectively to mobilized viscous hydrocarbons by the heated solvent
vapor stream when compared to the steam stream. With this in mind,
it is postulated that, in the 30.30 and 1.1 conditions, the steam
injection time period is sufficient to facilitate flow of the steam
stream to the interface region between the heated chamber and the
subterranean formation. In contrast, for the experimental
conditions in which the heated solvent vapor injection time is
significantly greater than the steam injection time, it is
postulated that the steam stream, or at least a majority of the
steam stream, does not reach the interface region.
[0038] FIG. 3 is a plot illustrating cumulative solvent-to-oil
ratio as a function of recovery factor for the experimental
conditions and/or injection strategies of FIG. 2. The cumulative
solvent-to-oil ratio is a ratio of a volume of solvent utilized to
produce a given volume of oil. A lower cumulative solvent-to-oil
ratio generally is considered to indicate an improved efficiency of
solvent utilization and/or lower solvent costs.
[0039] As may be seen from FIG. 3, for recovery factors greater
than approximately 5%, there is a systematic decrease in cumulative
solvent-to-oil ratio as an injection time ratio is decreased, with
the injection time ratio being a ratio of the heated solvent vapor
injection time period to the steam injection time period. This may
be evidenced by the systematic decrease in the cumulative
solvent-to-oil ratio when moving from the base case (for which the
injection time ratio arguably is infinite) to the 30.1 experimental
condition (30:1 injection time ratio) to the 30.2 and 15.1
experimental conditions (15:1 injection time ratio) to the 30.3 and
10.1 experimental conditions (10:1 injection time ratio) to the
30.30 and 1.1 experimental conditions (1:1 injection time
ratio).
[0040] FIG. 3 also illustrates that the cumulative solvent-to-oil
ratio also may be impacted, to some extent, not only by an absolute
magnitude of the injection time ratio but also by a magnitude of
the heated solvent vapor injection time period and/or by a
magnitude of the steam injection time period. This impact may be
evidenced by the difference between the 30.30 and 1.1 conditions in
FIG. 3.
[0041] The combination of FIGS. 2-3 illustrates that the methods
disclosed herein, which cyclically inject both heated solvent vapor
and steam, may be utilized to improve the cumulative solvent-to-oil
ratio when compared to methods that inject a heated solvent vapor
stream but do not inject a steam stream (i.e., the base condition
of FIGS. 2-3). However, this improvement in the cumulative
solvent-to-oil ratio may be balanced against a decrease in recovery
factor with time, at least for methods that utilize relatively
lower injection time ratios.
[0042] FIG. 4 is a flowchart depicting methods 100, according to
the present disclosure, for recovering viscous hydrocarbons from a
subterranean formation. Methods 100 may include forming one or more
wells at 105 and include injecting a heated solvent vapor stream at
110 and fluidly contacting viscous hydrocarbons with the heated
solvent vapor stream at 115. Methods 100 also may include
condensing the heated solvent vapor stream at 120, accumulating
chamber liquid at 125, monitoring a liquid level variable at 130,
and/or ceasing injection of the heated solvent vapor stream at 135.
Methods 100 also include injecting a steam stream at 140 and may
include ceasing injection of the steam stream at 145 and/or
draining mobilized viscous hydrocarbons at 150. Methods 100 further
include producing a produced fluid stream at 155 and may include
reducing a volume of chamber liquid at 165, maintaining a target
operating pressure at 170, and/or monitoring a composition variable
at 175. Methods 100 also include repeating the methods for a
plurality of injection cycles at 180.
[0043] Forming one or more wells at 105 may include forming any
suitable type, number, and/or configuration of well in any suitable
manner. The well may form a portion of a hydrocarbon production
system, such as hydrocarbon production system 10 of FIG. 1.
Examples of the well include an injection well and/or a production
well. The injection well, when formed, may include a horizontal, or
an at least substantially horizontal, region and/or portion.
Similarly, the production well, when formed, may include a
horizontal, or at least substantially horizontal, region and/or
portion. As illustrated in FIG. 1, the horizontal region of the
production well may extend below, vertically below, and/or at a
greater depth within the subterranean formation when compared to
the horizontal region of the injection well. FIGS. 5-8 are
schematic cross-sectional views illustrating examples of injection
wells 30 and/or production wells 40 that may be formed during the
forming at 105.
[0044] Injecting the heated solvent vapor stream at 110 may include
injecting any suitable heated solvent vapor stream into the
subterranean formation and/or into a heated chamber that extends
within the subterranean formation. The injecting at 110 may include
injecting with, via, and/or utilizing the injection well and/or the
horizontal region of the injection well.
[0045] The injecting at 110 also may include injecting for a heated
solvent vapor injection time period. Examples of the heated solvent
vapor injection time period include heated solvent vapor injection
time periods of at least 0.1 days, at least 0.25 days, at least 0.5
days, at least 1 day, at least 2 days, at least 3 days, at least 4
days, at least 5 days, at least 6 days, at least 8 days, at least
10 days, at least 15 days, at least 20 days, at least 25 days,
and/or at least 30 days. Additional examples of the heated solvent
vapor injection time period include heated solvent vapor injection
time periods of at most 45 days, at most 40 days, at most 35 days,
at most 30 days, at most 25 days, at most 20 days, at most 15 days,
at most 10 days, and/or at most 5 days.
[0046] The heated solvent vapor stream may have and/or define any
suitable composition or chemical composition that includes at least
50 weight percent nonaqueous species, which also may be referred to
herein as a solvent. The nonaqueous species non-negligibly
solubilizes and/or dissolves the viscous hydrocarbons and may
include a hydrocarbon, or a hydrocarbon solvent, examples of which
are disclosed herein. As an example, the heated solvent vapor
stream may consist of, or consist essentially of the nonaqueous
species. As another example, the heated solvent vapor stream may
include at least a threshold fraction of the nonaqueous species.
Examples of the threshold fraction of nonaqueous species include
threshold fractions of at least 50 weight percent (wt%), at least
51 wt %, at least 60 wt %, at least 70 wt %, at least 80 wt %, at
least 90 wt %, at least 95 wt %, and/or at least 99 wt %. As more
specific examples, the heated solvent vapor stream and/or the
nonaqueous species may include, consist of, and/or consist
essentially of one or more of a hydrocarbon, a hydrocarbon solvent,
an alkane, an alkene, an alkyne, an aliphatic compound, a
naphthenic compound, an aromatic compound, an olefinic compound,
natural gas condensate, liquefied petroleum gas, and/or a crude oil
refinery stream.
[0047] The heated solvent vapor stream also may include water
and/or steam. As an example, the heated solvent vapor stream may
include an azeotropic, or a near-azeotropic, mixture of hydrocarbon
solvent and water. Under these conditions, a solvent molar fraction
of the hydrocarbon solvent in the near-azeotropic mixture may be
70%-130% of an azeotropic molar fraction of the near-azeotropic
mixture at the target operating pressure within the heated
chamber.
[0048] It is within the scope of the present disclosure that a
bubble point temperature of the heated solvent vapor stream at the
target operating pressure within the heated chamber may be less
than a bubble point temperature of the steam stream at the target
operating pressure within the heated chamber. As such, and as
discussed in more detail herein, the injecting at 140 may
facilitate vaporization of condensed solvent within the heated
chamber.
[0049] It is within the scope of the present disclosure that the
injecting at 110 may be performed in a manner that is similar to
that of more conventional solvent-based thermal recovery processes.
As examples, the injecting at 110 may be performed in a manner that
is similar to, or may be performed as part of, a heated vapor
extraction process, an azeotropic heated vapor extraction process,
and/or a near-azeotropic heated vapor extraction process.
[0050] The injecting at 110 is illustrated schematically in FIG. 5.
As illustrated therein, an injectant stream 60, in the form of a
heated solvent vapor stream 62, may be injected into subterranean
formation 24 and/or into heated chamber 50 via an injection well
30.
[0051] Fluidly contacting viscous hydrocarbons with the heated
solvent vapor stream at 115 may include fluidly contacting to
produce and/or generate mobilized viscous hydrocarbons within the
heated chamber. This may be accomplished in any suitable manner. As
examples, the fluidly contacting at 115 may include one or more of
diluting the viscous hydrocarbons with the heated solvent vapor
stream to generate the mobilized viscous hydrocarbons, dissolving
the viscous hydrocarbons in the heated solvent vapor stream to
generate the mobilized viscous hydrocarbons, and/or heating the
viscous hydrocarbons with the heated solvent vapor stream to
generate the mobilized viscous hydrocarbons.
[0052] The fluidly contacting at 115 also is schematically
illustrated in FIG. 5. Therein, heated solvent vapor stream 62 may
flow, within the heated chamber, to an interface region 52 between
the heated chamber and the subterranean formation, may interact
with viscous hydrocarbons 26 that are present within subterranean
formation 24, and may generate a chamber liquid 70. Chamber liquid
70 may include and/or be mobilized viscous hydrocarbons 72 and/or
condensed solvent 78.
[0053] Condensing the heated solvent vapor stream at 120 may
include condensing the heated solvent vapor stream to produce
and/or form condensed solvent and/or to form the chamber liquid
that includes both the condensed solvent and the mobilized viscous
hydrocarbons. The condensing at 120 may be facilitated by,
responsive to, and/or a result of the fluidly contacting at 115. As
an example, and as discussed, the fluidly contacting at 115 may
include heating the viscous hydrocarbons to generate the mobilized
viscous hydrocarbons. Under these conditions, heating of the
viscous hydrocarbons may be accompanied by a corresponding decrease
in a temperature of the heated solvent vapor stream, thereby
causing the heated solvent vapor stream to release its heat of
condensation and transition from the vapor phase to the liquid
phase.
[0054] Additionally or alternatively, the condensing at 120 may be
facilitated by, responsive to, and/or a result of thermal and/or
fluid contact between the heated solvent vapor stream and
subterranean strata that extends within the heated chamber. As an
example, thermal and/or fluid contact between the heated solvent
vapor stream and the subterranean strata may facilitate thermal
energy transfer from the heated solvent vapor stream to the
subterranean strata, thereby causing the heated solvent vapor
stream to condense on the subterranean strata and generate the
condensed solvent.
[0055] Accumulating chamber liquid at 125 may include accumulating
the chamber liquid within the heated chamber. This may include
accumulating the chamber liquid, which may include both the
condensed solvent and the mobilized viscous hydrocarbons, to form a
chamber liquid pool within the heated chamber. Additionally or
alternatively, the accumulating at 125 may include accumulating the
chamber liquid such that, or until, the at least substantially
horizontal region of the injection well is at least partially
immersed, is immersed, is completely immersed, is at least
partially covered, is covered, and/or is completely covered by the
chamber liquid and/or within the chamber liquid pool.
[0056] Stated another way, the accumulating at 125 may include
accumulating such that the at least substantially horizontal region
of the injection well is below, or is a threshold di stance below,
an upper surface of the chamber liquid pool. Examples of the
threshold distance include threshold distances of at least 0.5
meters, at least 1 meter, at least 2 meters, at least 3 meters, at
least 4 meters, at most 8 meters, at most 6 meters, and/or at most
4 meters.
[0057] The accumulating at 125 may be accomplished in any suitable
manner. As an example, methods 100 may include ceasing the
producing at 160, such as to bring about, or facilitate, the
accumulating at 125. As another example, methods 100 may include
regulating a production rate of a produced chamber liquid that is
produced during the producing at 155 to bring about, or facilitate,
the accumulating at 125. As a more specific example, the
accumulating at 125 may include increasing the production rate of
the produced chamber liquid responsive to the upper surface of the
chamber liquid pool being above, or being greater than the
threshold distance above, the at least substantially horizontal
region of the injection well. As another more specific example, the
accumulating at 125 may include decreasing the production rate of
the produced chamber liquid responsive to the upper surface of the
chamber liquid pool being below, or being less than the threshold
distance above, the at least substantially horizontal region of the
injection well.
[0058] The accumulating at 125 is schematically illustrated in FIG.
6. As illustrated therein, the accumulating at 125 may include
accumulating chamber liquid 70 within heated chamber 50 such that
the at least substantially horizontal region of injection well 30
is immersed within the chamber liquid and/or within a chamber
liquid pool 74. The accumulating at 125 is illustrated in FIG. 6 by
the progression from an upper surface 76 of chamber liquid pool 74
being below injection well 30, as illustrated in dashed lines, to
the upper surface of the chamber liquid pool approaching the
injection well, as illustrated in dash-dot lines, to the upper
surface of the chamber liquid pool being above the injection well,
as illustrated in solid lines.
[0059] Monitoring the liquid level variable at 130 may include
monitoring any suitable liquid level variable that may be
associated with and/or indicative of a location of the upper
surface of the chamber liquid pool within the heated chamber. When
methods 100 include the monitoring at 130, the accumulating at 125
may be performed based, at least in part, on the liquid level
variable. As an example, the accumulating at 125 may include
increasing a height of a liquid level of the chamber liquid pool
and/or a depth of the chamber liquid pool, within the heated
chamber, until the monitoring at 130 indicates that the at least
substantially horizontal region of the injection well is immersed
within the chamber liquid. Examples of the liquid level variable
include one or more of a pressure within the heated chamber, a
pressure differential within the heated chamber, a pressure
differential between the injection well and the production well, a
pressure differential between two different depths within the
heated chamber, a temperature within the heated chamber, a
temperature differential within the heated chamber, a production
temperature of the produced fluid stream, a temperature
differential between a temperature of the heated solvent vapor
stream and a temperature of the produced fluid stream, a
temperature differential between the temperature of the produced
fluid stream and a bubble point temperature of the heated solvent
vapor stream, a temperature differential between the temperature of
the produced fluid stream and a dew point temperature of the heated
solvent vapor stream, a comparison between the temperature within
the heated chamber and an estimated bubble point temperature of the
chamber liquid, a change in a production temperature of mobilized
viscous hydrocarbons, the production temperature of the mobilized
viscous hydrocarbons, and/or a water-to-hydrocarbon ratio within
the produced chamber liquid.
[0060] Ceasing injection of the heated solvent vapor stream at 135
may be performed with any suitable timing within methods 100 and/or
in any suitable manner. As an example, the ceasing at 135 may
include ceasing injection of the heated solvent vapor stream
subsequent to the heated solvent vapor injection time period and/or
subsequent to performing the injecting at 110 for the heated
solvent vapor injection time period. As another example, the
ceasing at 135 may include ceasing injection of the heated solvent
vapor stream prior to the steam injection time period and/or prior
to initiation of the injecting at 140.
[0061] Injecting the steam stream at 140 may include injecting the
steam stream via the at least substantially horizontal region of
the injection well and/or into the heated chamber. The injecting at
140 may include injecting the steam stream subsequent to performing
the injecting at 110, injecting the steam stream subsequent to the
heated solvent vapor injection time period, and/or injecting the
steam stream for a steam injection time period.
[0062] It is within the scope of the present disclosure that the
injecting at 140 may include vaporizing, or injecting the steam
stream to vaporize, at least a fraction of the condensed solvent
that is present within the heated chamber. Additionally or
alternatively, the injecting at 140 may include vaporizing, or
injecting the steam stream to vaporize, at least a fraction of the
chamber liquid that may extend within the heated chamber and/or
that may define the chamber liquid pool. This may include
vaporizing the condensed solvent and/or the chamber liquid to
produce and/or generate vaporized solvent.
[0063] As discussed herein, the heated chamber may include and/or
define an interface region that extends between the heated chamber
and a remainder of the subterranean formation. Under these
conditions, the injecting at 140 may include injecting the steam
stream to facilitate, or provide a motive force for, flow of the
heated solvent vapor stream and/or the vaporized solvent toward
and/or into contact with the interface region.
[0064] This is illustrated schematically in FIG. 7. As illustrated
therein, injection of a steam stream 64 into heated chamber 50 via
injection well 30 may increase a pressure within a region 54 of
heated chamber 50 that is proximal to injection well 30 and/or may
vaporize condensed solvent within region 54. This increased
pressure may cause heated solvent vapor stream 62 and/or vaporized
solvent 66 to flow toward interface region 52, thereby increasing
an effectiveness of the injected solvent in recovering viscous
hydrocarbons 26 from the subterranean formation. Additionally or
alternatively, the injecting at 140 may include flushing condensed
solvent 78 from heated chamber 50, facilitating flow of the
condensed solvent from the heated chamber, and/or facilitating
condensation of the heated solvent vapor stream within the
interface region. As discussed herein, the steam injection time may
be selected such that region 54 does not extend into contact with
interface region 52 and/or such that injected solvent, in the form
of heated solvent vapor stream 62, vaporized solvent 66, and/or
condensed solvent 78, contacts interface region 52 to a greater
extent when compared to steam stream 64.
[0065] When methods 100 include the accumulating at 125, the
injecting at 140 additionally or alternatively may include
injecting, or initiating the injecting, subsequent to the
accumulating at 125 and/or subsequent to the at least substantially
horizontal region of the injection well being immersed within the
chamber liquid. Stated another way, the accumulating at 125 may be
performed prior to the injecting at 140. Under these conditions,
the injecting at 140 may include injecting such that the steam
stream contacts, directly contacts, flows through, and/or bubbles
through at least a region of the chamber liquid pool. Additionally
or alternatively, the injecting at 140 may include injecting such
that the steam stream vaporizes at least a fraction of the chamber
liquid, such as the condensed solvent, from the chamber liquid
pool. When methods 100 include the accumulating at 125, methods 100
further may include maintaining the at least substantially
horizontal region of the injection well immersed within the chamber
pool during the injecting at 140, during the steam injection time
period, during at least a substantial fraction of the steam
injection time period, during a majority of the steam injection
time period, and/or during an entirety of the steam injection time
period.
[0066] This is illustrated schematically in FIG. 8. As illustrated
therein, injection well 30 may be immersed within chamber liquid
pool 74 during the injecting at 140. As such, the injecting at 140
may include contacting steam stream 64 with chamber liquid 70
within chamber liquid pool 74. This contact between the steam
stream and the chamber liquid may facilitate thermal energy
transfer from the steam stream to the chamber liquid, vaporization
of condensed solvent 78 from the chamber liquid, and/or generation
of vaporized solvent 66.
[0067] It is within the scope of the present disclosure that
methods 100 may transition between the injecting at 110 to the
injecting at 140 based upon any suitable criteria. As an example,
the heated solvent vapor injection time period may be a
predetermined, or fixed, heated solvent vapor injection time
period. Under these conditions, methods 100 may transition from the
injecting at 110 to the injecting at 140 subsequent to, or
subsequent to expiration of, the heated solvent vapor injection
time period.
[0068] Additionally or alternatively, the heated solvent vapor
injection time period may be determined and/or established based,
at least in part, upon one or more properties and/or variables that
may be determined and/or measured during methods 100. Stated
another way, methods 100 may transition from the injecting at 110
to the injecting at 140 based, at least in part, on the one or more
properties and/or variables. Examples of the one or more properties
and/or variables include a change in a production rate of mobilized
viscous hydrocarbons from the subterranean formation during the
producing at 155; in the production rate, or a magnitude of the
production rate, of the mobilized viscous hydrocarbons; in a
concentration of solvent in the mobilized viscous hydrocarbons
produced from the subterranean formation; in the concentration, or
a magnitude of the concentration, of the solvent, and/or in a
temperature within the heated chamber.
[0069] The steam injection time period may have any suitable
duration. As examples, the steam injection time period may be at
least 0.1 days, at least 0.25 days, at least 0.5 days, at least
0.75 days, at least 1 day, at least 1.5 days, at least 2 days, at
least 3 days, at least 4 days, at least 5 days, at least 6 days, at
least 8 days, at least 10 days, and/or at least 15 days.
Additionally or alternatively, the steam injection time period may
be at most 15 days, at most 10 days, at most 8 days, at most 6
days, at most 5 days, at most 4 days, at most 3 days, at most 2
days, and/or at most 1 day.
[0070] Additionally or alternatively, the heated solvent vapor
injection time period and the steam injection time period may have
any suitable relative magnitude. As an example, method 100 may
define an injection time ratio of the heated solvent vapor
injection time period to the steam injection time period. Examples
of the injection time ratio include injection time ratios of at
least 1, at least 2, at least 3, at least 4, at least 5, at least
6, at least 8, at least 10, at least 15, at least 20, at least 25,
at least 30, at least 40, and/or at least 50. Additionally or
alternatively, the injection time ratio may be at most 100, at most
80, at most 60, at most 50, at most 40, at most 30, at most 25, at
most 20, at most 15, and/or at most 10. The injection time ratio
may be selected to prevent, or to decrease a potential for, fluid
contact between the steam stream and the interface region.
[0071] Additionally or alternatively, methods 100 may define an
injection mass ratio. As an example, the injecting at 110 may
include injecting a mass of heated solvent vapor, the injecting at
140 may include injecting a mass of steam, and the injection mass
ratio may be a ratio of the mass of heated solvent vapor to the
mass of steam. The injecting at 110 and the injecting at 140 may be
performed such that the injection mass ratio has any suitable
value, or magnitude. As examples, the injection mass ratio may be
at least 1, at least 1.25, at least 1.5, at least 2, at least 3, at
least 4, at least 6, at least 8, at least 10, at least 12.5, at
least 15, at least 20, at least 25, and/or at least 30.
Additionally or alternatively, the injection mass ratio may be at
most 100, at most 80, at most 60, at most 50, at most 40, at most
30, at most 25, at most 20, at most 15, and/or at most 10.
[0072] The injecting at 140 may include injecting a steam stream
with any suitable composition. As an example, the steam stream may
include, may consist of, and/or may consist essentially of steam
and/or water. As another example, the steam stream may include,
have, and/or define at least a threshold fraction of steam.
Examples of the threshold fraction of steam include threshold
fractions of at least 51 wt %, at least 60 wt %, at least 70 wt %,
at least 80 wt %, at least 90 wt %, at least 95 wt %, and/or at
least 99 wt %. Ceasing injection of the steam stream at 145 may
include ceasing supply of the steam stream to the subterranean
formation and/or to the heated chamber via the injection well.
Stated another way, the ceasing at 145 may include ceasing the
injecting at 140.
[0073] The ceasing at 145 may be performed subsequent to the steam
injection time period and/or prior to the repeating at 180. Stated
another way, and within a given injection cycle of the plurality of
injection cycles, the ceasing at 145 may be performed prior to
performing the injecting at 110 for a subsequent injection cycle of
the plurality of injection cycles.
[0074] Draining mobilized viscous hydrocarbons at 150 may include
draining the mobilized viscous hydrocarbons under the influence of
gravity. This may include draining the mobilized viscous
hydrocarbons toward and/or into a lower region of the heated
chamber that includes the at least substantially horizontal region
of the production well. Additionally or alternatively, the draining
at 150 may include draining the mobilized viscous hydrocarbons
toward and/or into the production well. This is illustrated
schematically in FIGS. 5-8, with the arrows indicating drainage of
chamber liquid 70, including mobilized viscous hydrocarbons 72
thereof, toward production well 40.
[0075] Producing the produced fluid stream at 155 may include
producing the chamber liquid, the mobilized viscous hydrocarbons,
and/or the condensed solvent from the heated chamber and/or from
the subterranean formation. This may include producing with, via,
and/or utilizing the production well, or the at least substantially
horizontal region of the production well. The chamber liquid may be
produced from the subterranean formation as a produced chamber
liquid. Similarly, the mobilized viscous hydrocarbons may be
produced from the subterranean formation as produced mobilized
viscous hydrocarbons, and/or the condensed solvent may be produced
from the subterranean formation as produced condensed solvent.
[0076] The producing at 155 may be performed with any suitable
timing and/or sequence during methods 100. As an example, the
producing at 155 may be performed during at least one injection
cycle of the plurality of injection cycles. As another example, the
producing at 155 may be performed during each injection cycle of
the plurality of injection cycles. As yet another example, the
producing at 155 may be performed during at least a portion of the
heated solvent vapor injection time period, during an entirety of
the heated solvent vapor injection time period, during the
injecting at 110, during the fluidly contacting at 115, during at
least a portion of the steam injection time period, during an
entirety of the steam injection time period, and/or during the
injecting at 140. Stated another way, it is within the scope of the
present disclosure that methods 100 may include continuously
performing the producing at 155 or intermittently performing the
producing at 155. When methods 100 include intermittently
performing the producing at 155, methods 100 may include ceasing
the producing at 160 prior to the injecting at 140 and/or during
the injecting at 140, such as to facilitate the accumulating at
125, when performed.
[0077] As discussed herein, the at least substantially horizontal
region of the production well may extend within the heated chamber
and below the at least substantially horizontal region of the
injection well. It is within the scope of the present disclosure
that the at least substantially horizontal region of the production
well and the at least substantially horizontal region of the
injection well may define any suitable spacing, or average spacing,
therebetween. In addition, and when methods 100 include the forming
at 105, the forming at 105 may include forming such that the at
least substantially horizontal region of the production well and
the at least substantially horizontal region of the injection well
have and/or define the average spacing. Examples of the average
spacing include average spacings of at least 1 meter, at least 2
meters, at least 3 meters, at least 4 meters, at least 5 meters, at
most 10 meters, at most 8 meters, at most 5 meters, at most 4
meters, at most 3 meters, and/or at most 2 meters.
[0078] Reducing the volume of chamber liquid at 165 may include
reducing the volume of chamber liquid within, or that defines, the
chamber liquid pool. Stated another way, the reducing at 165 may
include reducing the volume of chamber liquid within the heated
chamber. This may include reducing such that the at least
substantially horizontal region of the injection well extends
above, or is not immersed in, the chamber liquid pool.
[0079] The reducing at 165 may be performed at any suitable time
and/or with any suitable sequence during methods 100. As an
example, methods 100 may include performing the reducing at 165
subsequent to performing the injecting at 140. As another example,
and within each injection cycle of the plurality of injection
cycles, methods 100 may include performing the reducing at 165
prior to performing the injecting at 110.
[0080] Maintaining the target operating pressure at 170 may include
maintaining the target operating pressure in, or within, the heated
chamber. This may include performing the injecting at 110 at, or to
maintain, the target operating pressure and/or performing the
injecting at 140 at, or to maintain, the target operating pressure.
Additionally or alternatively, the maintaining at 170 may include
selectively varying a temperature of the heated solvent vapor
stream and/or a temperature of the steam stream to maintain the
target operating pressure within the heated chamber.
[0081] Monitoring the composition variable at 175 may include
monitoring any suitable composition variable that may be associated
with a solvent content of the produced chamber liquid. Examples of
the composition variable include a density of the produced chamber
liquid, a viscosity of the produced chamber liquid, and/or a
chemical composition of the produced chamber liquid.
[0082] When methods 100 include the monitoring at 175, methods 100
also may include selectively regulating the injecting at 110 based,
at least in part, on the monitoring at 175. As an example, methods
100 may include selectively regulating an injection rate of the
heated solvent vapor stream based, at least in part, on the
composition variable. This may include selectively increasing the
injection rate of the heated solvent vapor stream responsive to a
decrease in the solvent content of the produced chamber liquid
and/or selectively increasing the injection rate of the heated
solvent vapor stream responsive to an increase in the solvent
content of the produced chamber liquid.
[0083] When methods 100 include the monitoring at 175, methods 100
also may include selectively regulating the injecting at 140 based,
at least in part, on the monitoring at 175. As an example, methods
100 may include selectively regulating an injection rate of the
steam stream based, at least in part, on the composition variable.
This may include selectively increasing the injection rate of the
steam stream responsive to an increase in the solvent content of
the produced chamber liquid and/or selectively decreasing the
injection rate of the steam stream responsive to a decrease in the
solvent content of the produced chamber liquid.
[0084] When methods 100 include the monitoring at 175, methods 100
also may include selectively regulating the producing at 155 based,
at least in part, on the monitoring at 175. As an example, methods
100 may include selectively regulating a production rate of the
chamber liquid based, at least in part, on the composition
variable. This may include selectively increasing the production
rate of the chamber liquid to decrease the volume of chamber liquid
within the heated chamber and/or selectively decreasing the
production rate of the chamber liquid to increase the volume of the
chamber liquid within the heated chamber.
[0085] Repeating the methods for the plurality of injection cycles
at 180 may include repeating at least the injecting at 110, the
fluidly contacting at 115, and the injecting at 140 during each of
the plurality of injection cycles. Stated another way, methods 100
may include sequentially performing the injecting at 110, the
fluidly contacting at 115, and the injecting at 140 for a plurality
of distinct injection cycles. The repeating at 180 also may include
repeating the producing at 155 during each of the plurality of
injection cycles.
[0086] It is within the scope of the present disclosure that
methods 100 may include transition from a given injection cycle of
the plurality of injection cycles to a subsequent injection cycle
of the plurality of injection cycles based upon any suitable
criteria. As an example, methods 100 may transition from the given
injection cycle to the subsequent injection cycle responsive to
completion of the injecting at 140 and/or responsive to expiration
of the steam injection time period. As another example, methods 100
may include ceasing the injecting at 140, and/or transitioning from
the given injection cycle to the subsequent injection cycle,
responsive to the composition variable associated with the solvent
content of the produced chamber liquid indicating less than a
threshold solvent content within the produced chamber liquid.
[0087] It also is within the scope of the present disclosure that
methods 100 may include modifying the injecting at 110 and/or the
injecting at 140 in a given injection cycle of the plurality of
injection cycles relative to a prior injection cycle of the
plurality of injection cycles. As an example, and as discussed
herein, performing methods 100 may cause the heated chamber to
grow, or expand, with time. As such, and responsive to an increase
in a volume of the heated chamber, methods 100 may include
increasing the injection time ratio in the given injection cycle
relative to the prior injection cycle. As additional examples,
methods 100 may include modifying the injection time ratio in the
given injection cycle relative to the prior injection cycle based,
at least in part, on a change in a production rate of mobilized
viscous hydrocarbons, on the production rate of mobilized viscous
hydrocarbons, on a change in a concentration of solvent in the
mobilized viscous hydrocarbons produced from the subterranean
formation, on the concentration of the mobilized viscous
hydrocarbons produced from the subterranean formation, on a
temperature within the heated chamber, on a change in a production
temperature of the mobilized viscous hydrocarbons, and/or on the
production temperature of the mobilized viscous hydrocarbons.
[0088] In the present disclosure, several of the illustrative,
non-exclusive examples have been discussed and/or presented in the
context of flow diagrams, or flow charts, in which the methods are
shown and described as a series of blocks, or steps. Unless
specifically set forth in the accompanying description, it is
within the scope of the present disclosure that the order of the
blocks may vary from the illustrated order in the flow diagram,
including with two or more of the blocks (or steps) occurring in a
different order and/or concurrently.
[0089] As used herein, the term "and/or" placed between a first
entity and a second entity means one of (1) the first entity, (2)
the second entity, and (3) the first entity and the second entity.
Multiple entities listed with "and/or" should be construed in the
same manner, i.e., "one or more" of the entities so conjoined.
Other entities may optionally be present other than the entities
specifically identified by the "and/or" clause, whether related or
unrelated to those entities specifically identified. Thus, as a
non-limiting example, a reference to "A and/or B," when used in
conjunction with open-ended language such as "comprising" may
refer, in one embodiment, to A only (optionally including entities
other than B); in another embodiment, to B only (optionally
including entities other than A); in yet another embodiment, to
both A and B (optionally including other entities). These entities
may refer to elements, actions, structures, steps, operations,
values, and the like.
[0090] As used herein, the phrase "at least one," in reference to a
list of one or more entities should be understood to mean at least
one entity selected from any one or more of the entities in the
list of entities, but not necessarily including at least one of
each and every entity specifically listed within the list of
entities and not excluding any combinations of entities in the list
of entities. This definition also allows that entities may
optionally be present other than the entities specifically
identified within the list of entities to which the phrase "at
least one" refers, whether related or unrelated to those entities
specifically identified. Thus, as a non-limiting example, "at least
one of A and B" (or, equivalently, "at least one of A or B," or,
equivalently "at least one of A and/or B") may refer, in one
embodiment, to at least one, optionally including more than one, A,
with no B present (and optionally including entities other than B);
in another embodiment, to at least one, optionally including more
than one, B, with no A present (and optionally including entities
other than A); in yet another embodiment, to at least one,
optionally including more than one, A, and at least one, optionally
including more than one, B (and optionally including other
entities). In other words, the phrases "at least one," "one or
more," and "and/or" are open-ended expressions that are both
conjunctive and disjunctive in operation. For example, each of the
expressions "at least one of A, B, and C," "at least one of A, B,
or C," "one or more of A, B, and C," "one or more of A, B, or C,"
and "A, B, and/or C" may mean A alone, B alone, C alone, A and B
together, A and C together, B and C together, A, B and C together,
and optionally any of the above in combination with at least one
other entity.
[0091] As used herein the terms "adapted" and "configured" mean
that the element, component, or other subject matter is designed
and/or intended to perform a given function. Thus, the use of the
terms "adapted" and "configured" should not be construed to mean
that a given element, component, or other subject matter is simply
"capable of" performing a given function but that the element,
component, and/or other subject matter is specifically selected,
created, implemented, utilized, programmed, and/or designed for the
purpose of performing the function. It is also within the scope of
the present disclosure that elements, components, and/or other
recited subject matter that is recited as being adapted to perform
a particular function may additionally or alternatively be
described as being configured to perform that function, and vice
versa.
[0092] As used herein, the phrase, "for example," the phrase, "as
an example," and/or simply the term "example," when used with
reference to one or more components, features, details, structures,
embodiments, and/or methods according to the present disclosure,
are intended to convey that the described component, feature,
detail, structure, embodiment, and/or method is an illustrative,
non-exclusive example of components, features, details, structures,
embodiments, and/or methods according to the present disclosure.
Thus, the described component, feature, detail, structure,
embodiment, and/or method is not intended to be limiting, required,
or exclusive/exhaustive; and other components, features, details,
structures, embodiments, and/or methods, including structurally
and/or functionally similar and/or equivalent components, features,
details, structures, embodiments, and/or methods, are also within
the scope of the present disclosure.
Embodiments
[0093] Additional embodiments of the invention herein are as
follows:
[0094] Embodiment 1: A method for recovering viscous hydrocarbons
from a subterranean formation, the method comprising: [0095] a
plurality of injection cycles, wherein each injection cycle in the
plurality of injection cycles includes: injecting, via an at least
substantially horizontal region of an injection well and for a
heated solvent vapor injection time period, a heated solvent vapor
stream into a heated chamber that extends within the subterranean
formation, wherein the heated solvent vapor stream includes at
least 50 weight percent nonaqueous species; [0096] (ii) fluidly
contacting the viscous hydrocarbons with the heated solvent vapor
stream to generate mobilized viscous hydrocarbons within the heated
chamber; and [0097] (iii) subsequent to the heated solvent vapor
injection time period and for a steam injection time period,
injecting, via the at least substantially horizontal region of the
injection well, a steam stream into the heated chamber; and [0098]
during at least one injection cycle of the plurality of injection
cycles, producing the mobilized viscous hydrocarbons from the
subterranean formation via an at least substantially horizontal
region of a production well that extends within the heated chamber
and below the at least substantially horizontal region of the
injection well.
[0099] Embodiment 2: The method of embodiment 1, wherein the
subterranean formation includes subterranean strata, which extend
within the heated chamber, wherein the method further includes
condensing the heated solvent vapor stream on the subterranean
strata to generate condensed solvent, and further wherein the
injecting the steam stream includes vaporizing the condensed
solvent to generate vaporized solvent.
[0100] Embodiment 3: The method of any one of embodiments 1-2,
wherein the subterranean formation includes an interface region,
which extends between the heated chamber and a remainder of the
subterranean formation, and further wherein the injecting the steam
stream includes at least one of: [0101] (i) facilitating flow of
the heated solvent vapor stream into fluid contact with the
interface region; and [0102] (ii) facilitating flow of a/the
vaporized solvent into fluid contact with the interface region.
[0103] Embodiment 4: The method of any one of embodiments 1-3,
wherein the injecting the steam stream includes flushing condensed
solvent from the heated chamber.
[0104] Embodiment 5: The method of embodiment 4, wherein the
flushing includes facilitating flow of the condensed solvent from
the subterranean formation via the production well.
[0105] Embodiment 6: The method of any one of embodiments 4-5,
wherein the flushing includes facilitating condensation of the
heated solvent vapor stream within an/the interface region that
extends between the heated chamber and a remainder of the
subterranean formation.
[0106] Embodiment 7: The method of any one of embodiments 1-6,
wherein the method defines an injection time ratio of the heated
solvent vapor injection time period to the steam injection time
period.
[0107] Embodiment 8: The method of embodiment 7, wherein, during
each injection cycle of the plurality of injection cycles, the
injection time ratio is one of: [0108] (i) at least 1; [0109] (ii)
at least 2 [0110] (iii) at least 3; [0111] (iv) at least 4; [0112]
(v) at least 5; [0113] (vi) at least 6; [0114] (vii) at least 8;
[0115] (viii) at least 10; [0116] (ix) at least 15; [0117] (x) at
least 20; [0118] (xi) at least 25; [0119] (xii) at least 30; [0120]
(xiii) at least 40; and [0121] (xiv) at least 50.
[0122] Embodiment 9: The method of any one of embodiments 7-8,
wherein the injection time ratio is at least 1 and one of: [0123]
(i) at most 100; [0124] (ii) at most 80; [0125] (iii) at most 60;
[0126] (iv) at most 50; [0127] (v) at most 40; [0128] (vi) at most
30; [0129] (vii) at most 25; [0130] (viii) at most 20; [0131] (ix)
at most 15; and [0132] (x) at most 10.
[0133] Embodiment 10: The method of any one of embodiments 7-8,
wherein the injection time ratio is selected to prevent fluid
contact between the steam stream and an/the interface region that
extends between the heated chamber and a remainder of the
subterranean formation.
[0134] Embodiment 11: The method of any one of embodiments 7-10,
wherein, responsive to an increase in a volume of the heated
chamber, the method further includes increasing the injection time
ratio in a given injection cycle of the plurality of injection
cycles relative to a prior injection cycle of the plurality of
injection cycles.
[0135] Embodiment 12: The method of any one of embodiments 7-11,
wherein the method further includes modifying the injection time
ratio for a/the given injection cycle of the plurality of injection
cycles relative to a/the prior injection cycle of the plurality of
injection cycles based, at least in part, on at least one of: a
change in a production rate of mobilized viscous hydrocarbons;
[0136] (ii) the production rate of mobilized viscous hydrocarbons;
[0137] (iii) a change in a concentration of solvent in the
mobilized viscous hydrocarbons produced from the subterranean
formation; [0138] (iv) the concentration of solvent in the
mobilized viscous hydrocarbons produced from the subterranean
formation; [0139] (v) a change in a production temperature of the
mobilized viscous hydrocarbons; [0140] (vi) the production
temperature of the mobilized viscous hydrocarbons; and [0141] (vii)
a temperature within the heated chamber.
[0142] Embodiment 13: The method of any one of embodiments 1-12,
wherein the method further includes transitioning from the
injecting the heated solvent vapor stream to the injecting the
steam stream based, at least in part, on at least one of: [0143]
(i) a/the change in a production rate of mobilized viscous
hydrocarbons; [0144] (ii) the production rate of mobilized viscous
hydrocarbons; [0145] (iii) a/the change in a concentration of
solvent in the mobilized viscous hydrocarbons produced from the
subterranean formation; [0146] (iv) the concentration of solvent in
the mobilized viscous hydrocarbons produced from the subterranean
formation; [0147] (v) a/the change in a/the production temperature
of the mobilized viscous hydrocarbons; [0148] (vi) the production
temperature of the mobilized viscous hydrocarbons; and [0149] (vii)
a/the temperature within the heated chamber.
[0150] Embodiment 14: The method of any one of embodiments 1-13,
wherein the heated solvent vapor injection time period is one of:
[0151] (i) at least 0.1 days; [0152] (ii) at least 0.25 days;
[0153] (iii) at least 0.5 days; [0154] (iv) at least 1 day; [0155]
(v) at least 2 days; [0156] (vi) at least 3 days; [0157] (vii) at
least 4 days; [0158] (viii) at least 5 days; [0159] (ix) at least 6
days; [0160] (x) at least 8 days; [0161] (xi) at least 10 days;
[0162] (xii) at least 15 days; [0163] (xiii) at least 20 days;
[0164] (xiv) at least 25 days; and [0165] (xv) at least 30
days.
[0166] Embodiment 15: The method of any one of embodiments 1-14,
wherein the heated solvent vapor injection time period is at least
1 and one of: [0167] (i) at most 45 days; [0168] (ii) at most 40
days; [0169] (iii) at most 35 days; [0170] (iv) at most 30 days;
[0171] (v) at most 25 days; [0172] (vi) at most 20 days; [0173]
(vii) at most 15 days; [0174] (viii) at most 10 days; and [0175]
(ix) at most 5 days.
[0176] Embodiment 16: The method of any one of embodiments 1-15,
wherein the steam injection time period is one of: [0177] (i) at
least 0.1 days; [0178] (ii) at least 0.25 days; [0179] (iii) at
least 0.5 days; [0180] (iv) at least 0.75 days; [0181] (v) at least
1 day; [0182] (vi) at least 1.5 days; [0183] (vii) at least 2 days;
[0184] (viii) at least 4 days; [0185] (ix) at least 6 days; [0186]
(x) at least 8 days; and [0187] (xi) at least 10 days.
[0188] Embodiment 17: The method of any one of embodiments 1-16,
wherein the steam injection time period is at least 1 and one of:
[0189] (i) at most 15 days; [0190] (ii) at most 10 days; [0191]
(iii) at most 8 days; [0192] (iv) at most 6 days; [0193] (v) at
most 5 days; [0194] (vi) at most 4 days; [0195] (vii) at most 3
days; [0196] (viii) at most 2 days; and [0197] (ix) at most 1
day.
[0198] 18. The method of any one of embodiments 1-17, wherein the
injecting the heated solvent vapor stream includes injecting a mass
of heated solvent vapor, and further wherein the injecting the
steam stream includes injecting a mass of steam.
[0199] Embodiment 19: The method of embodiment 18, wherein, during
each injection cycle of the plurality of injection cycles, an
injection mass ratio of the mass of heated solvent vapor to the
mass of steam is one of: [0200] (i) at least 1.0; [0201] (ii) at
least 1.25; [0202] (iii) at least 1.5; [0203] (iv) at least 2.0;
[0204] (v) at least 3; [0205] (vi) at least 4; [0206] (vii) at
least 6; [0207] (viii) at least 8; [0208] (ix) at least 10; [0209]
(x) at least 12.5; [0210] (xi) at least 15; [0211] (xii) at least
20; [0212] (xiii) at least 25; and [0213] (xiv) at least 30.
[0214] Embodiment 20: The method of any one of embodiments 1-19,
wherein the method further includes maintaining a target operating
pressure within the heated chamber.
[0215] Embodiment 21: The method of embodiment 20, wherein the
maintaining includes performing the injecting the heated solvent
vapor stream and the injecting the steam stream at the target
operating pressure.
[0216] Embodiment 22: The method of any one of embodiments 20-21,
wherein the maintaining includes selectively varying at least one
of a temperature of the heated solvent vapor stream and a
temperature of the steam stream to maintain the target operating
pressure.
[0217] Embodiment 23: The method of any one of embodiments 1-22,
wherein the fluidly contacting includes condensing the heated
solvent vapor stream to form a chamber liquid that includes
condensed solvent and the mobilized viscous hydrocarbons, wherein
the producing includes producing at least a portion of the chamber
liquid as a produced chamber liquid, and further wherein: prior to
the injecting the steam stream, the method includes accumulating
the chamber liquid within the heated chamber to form a chamber
liquid pool within the heated chamber and immersing the at least
substantially horizontal region of the injection well within the
chamber liquid pool; and [0218] (ii) initiating the injecting the
steam stream subsequent to the at least substantially horizontal
region of the injection well being immersed within the chamber
liquid pool.
[0219] Embodiment 24: The method of embodiment 23, wherein the
accumulating includes accumulating such that the at least
substantially horizontal region of the injection well is completely
immersed within the chamber liquid pool.
[0220] Embodiment 25: The method of any one of embodiments 23-24,
wherein the accumulating includes accumulating such that the at
least substantially horizontal region of the injection well is a
threshold distance below an upper surface of the chamber liquid
pool.
[0221] Embodiment 26: The method of embodiment 25, wherein the
threshold distance is at least one of: [0222] (i) at least 0.5
meters; [0223] (ii) at least 1 meter; [0224] (iii) at least 2
meters; [0225] (iv) at least 3 meters; [0226] (v) at least 4
meters; [0227] (vi) at most 8 meters; [0228] (vii) at most 6
meters; and [0229] (viii) at most 4 meters.
[0230] Embodiment 27: The method of any one of embodiments 23-26,
wherein the accumulating includes regulating a production rate of
the produced chamber liquid to increase a volume of the chamber
liquid within the heated chamber.
[0231] Embodiment 28: The method of embodiment 27, wherein the
regulating includes at least one of: [0232] (i) increasing the
production rate of the produced chamber liquid responsive to an/the
upper surface of the chamber liquid pool being above the at least
substantially horizontal region of the injection well; [0233] (ii)
increasing the production rate of the produced chamber liquid
responsive to the upper surface of the chamber liquid pool being
greater than a/the threshold distance above the at least
substantially horizontal region of the injection well; and [0234]
(iii) decreasing the production rate of the produced chamber liquid
responsive to the upper surface of the chamber liquid pool being
below the at least substantially horizontal region of the injection
well.
[0235] Embodiment 29: The method of any one of embodiments 23-28,
wherein the injecting the steam stream includes utilizing the steam
stream to vaporize at least a fraction of the condensed solvent
from the chamber liquid pool.
[0236] Embodiment 30: The method of any one of embodiments 23-29,
wherein the method further includes monitoring a composition
variable associated with a solvent content of the produced chamber
liquid.
[0237] Embodiment 31: The method of embodiment 30, wherein the
method further includes at least one of: [0238] (i) selectively
regulating an injection rate of the heated solvent vapor stream
based, at least in part, on the composition variable; and [0239]
(ii) selectively regulating an injection rate of the steam stream
based, at least in part, on the composition variable.
[0240] Embodiment 32: The method of any one of embodiments 30-31,
wherein the monitoring the composition variable includes at least
one of: [0241] (i) monitoring a density of the produced chamber
liquid; [0242] (ii) monitoring a viscosity of the produced chamber
liquid; and [0243] (iii) monitoring a chemical composition of the
produced chamber liquid.
[0244] Embodiment 33: The method of any one of embodiments 23-32,
wherein the method further includes monitoring a liquid level
variable associated with a location of an/the upper surface of the
chamber liquid pool within the heated chamber, and further wherein
the accumulating is based, at least in part, on the liquid level
variable.
[0245] Embodiment 34: The method of embodiment 33, wherein the
monitoring the liquid level variable includes at least one of:
[0246] (i) monitoring at least one pressure within the heated
chamber; [0247] (ii) monitoring a differential pressure between two
different depths within the heated chamber; [0248] (iii) monitoring
at least one temperature within the heated chamber and comparing
the at least one temperature to an estimated bubble point
temperature of the chamber liquid; [0249] (iv) monitoring a
temperature differential within the heated chamber; [0250] (v)
monitoring a change in a production temperature of the mobilized
viscous hydrocarbons; [0251] (vi) monitoring the production
temperature of the mobilized viscous hydrocarbons; and [0252] (vii)
monitoring a water-to-hydrocarbon ratio within the produced chamber
liquid.
[0253] Embodiment 35: The method of any one of embodiments 23-34,
wherein, during the injecting the steam stream, the method includes
maintaining the at least substantially horizontal region of the
injection well immersed within the chamber liquid pool.
[0254] Embodiment 36: The method of any one of embodiments 23-35,
wherein, subsequent to the injecting the steam stream, the method
further includes reducing a volume of chamber liquid within the
heated chamber such that the at least substantially horizontal
region of the injection well extends above an/the upper surface of
the chamber liquid pool.
[0255] Embodiment 37: The method of embodiment 36, wherein, within
each injection cycle of the plurality of injection cycles, the
method includes performing the reducing the volume of chamber
liquid within the heated chamber prior to the injecting the heated
solvent vapor stream.
[0256] Embodiment 38: The method of any one of embodiments 23-37,
wherein the heated solvent vapor injection time period is at least
one of: [0257] (i) a predetermined heated solvent vapor injection
time period; and [0258] (ii) a fixed heated solvent vapor injection
time period.
[0259] Embodiment 39: The method of any one of embodiments 23-38,
wherein the method includes ceasing the injecting the steam stream
responsive to a/the composition variable associated with a/the
solvent content of the produced chamber liquid indicating less than
a threshold solvent content in the produced chamber liquid.
[0260] Embodiment 40: The method of any one of embodiments 23-39,
wherein the method includes ceasing the producing at least one of:
[0261] (i) prior to the injecting the steam stream; and [0262] (ii)
during the injecting the steam stream.
[0263] Embodiment 41: The method of any one of embodiments 23-40,
wherein the heated solvent vapor injection time period is one of:
[0264] (i) at least 1 day; [0265] (ii) at least 3 days; [0266]
(iii) at least 5 days; [0267] (iv) at least 10 days; and [0268] (v)
at least 15 days.
[0269] Embodiment 42. The method of any one of embodiments 23-41,
wherein the steam injection time period is one of: [0270] (i) at
least 1 day; [0271] (ii) at least 3 days; [0272] (iii) at least 5
days; [0273] (iv) at least 10 days; and [0274] (v) at least 15
days.
[0275] Embodiment 43: The method of any one of embodiments 1-42,
wherein, subsequent to the heated solvent vapor injection time
period, the method further includes ceasing the injecting the
heated solvent vapor stream.
[0276] Embodiment 44: The method of any one of embodiments 1-43,
wherein, prior to the steam injection time period, the method
further includes ceasing the injecting the heated solvent vapor
stream.
[0277] Embodiment 45: The method of any one of embodiments 1-44,
wherein, subsequent to the steam injection time period, the method
further includes ceasing the injecting the steam stream and
resuming the injecting the heated solvent vapor stream.
[0278] Embodiment 46: The method of any one of embodiments 1-45,
wherein the method further includes ceasing the injecting the steam
stream during a given injection cycle of the plurality of injection
cycles prior to performing the injecting the heated solvent vapor
stream during a subsequent injection cycle of the plurality of
injection cycles.
[0279] Embodiment 47: The method of any one of embodiments 1-46,
wherein the injecting the heated solvent vapor stream includes
injecting such that the heated solvent vapor stream includes at
least a threshold fraction of nonaqueous species.
[0280] Embodiment 48: The method of embodiment 47, wherein the
threshold fraction of nonaqueous species is one of: [0281] (i) at
least 51 weight percent (wt%); [0282] (ii) at least 60 wt %; [0283]
(iii) at least 70 wt %; [0284] (iv) at least 80 wt %; [0285] (v) at
least 90 wt %; [0286] (vi) at least 95 wt %; and [0287] (vii) at
least 99 wt %.
[0288] Embodiment 49: The method of any one of embodiments 1-48,
wherein the heated solvent vapor stream consists essentially of
solvent.
[0289] Embodiment 50: The method of any one of embodiments 1-49,
wherein the heated solvent vapor stream includes at least one of:
[0290] (i) a hydrocarbon; [0291] (ii) an alkane; [0292] (iii) an
alkene; [0293] (iv) an alkyne; [0294] (v) an aliphatic compound;
[0295] (vi) a naphthenic compound; [0296] (vii) an aromatic
compound; [0297] (viii) an olefinic compound; [0298] (ix) natural
gas condensate; [0299] (x) liquefied petroleum gas; and [0300] (xi)
a crude oil refinery stream.
[0301] Embodiment 51: The method of any one of embodiments 1-50,
wherein the heated solvent vapor stream includes at least one of
water and steam.
[0302] Embodiment 52: The method of any one of embodiments 1-51,
wherein the heated solvent vapor stream includes a near-azeotropic
mixture of a hydrocarbon solvent and water.
[0303] Embodiment 53: The method of embodiment 52, wherein a
solvent molar fraction of the hydrocarbon solvent in the
near-azeotropic mixture is 70%-130% of an azeotropic solvent molar
fraction of the near-azeotropic mixture at a target operating
pressure within the heated chamber.
[0304] Embodiment 54: The method of any one of embodiments 1-53,
wherein a bubble point temperature of the heated solvent vapor
stream at a/the target operating pressure within the heated chamber
is less than a bubble point temperature of the steam stream at the
target operating pressure within the heated chamber.
[0305] Embodiment 55: The method of any one of embodiments 1-54,
wherein the injecting the heated solvent vapor stream includes
injecting as part of at least one of: [0306] (i) a heated vapor
extraction process; and [0307] (ii) an azeotropic heated vapor
extraction process.
[0308] Embodiment 56: The method of any one of embodiments 1-55,
wherein the injecting the steam stream includes injecting such that
the steam stream includes at least a threshold fraction of
steam.
[0309] Embodiment 57: The method of embodiment 56, wherein the
threshold fraction of steam is one of: [0310] (i) at least 51
weight percent (wt%); [0311] (ii) at least 60 wt %; [0312] (iii) at
least 70 wt %; [0313] (iv) at least 80 wt %; [0314] (v) at least 90
wt %; [0315] (vi) at least 95 wt %; and [0316] (vii) at least 99 wt
%.
[0317] Embodiment 58: The method of any one of embodiments 1-57,
wherein the steam stream consists essentially of steam.
[0318] Embodiment 59: The method of any one of embodiments 1-58,
wherein the producing the mobilized viscous hydrocarbons includes
at least one of: [0319] (i) continuously producing the mobilized
viscous hydrocarbons during the method; and [0320] (ii)
intermittently producing the mobilized viscous hydrocarbons during
the method.
[0321] Embodiment 60: The method of any one of embodiments 1-59,
wherein the producing the mobilized viscous hydrocarbons includes
one of: [0322] (i) producing the mobilized viscous hydrocarbons
during the injecting the heated solvent vapor stream; [0323] (ii)
producing the mobilized viscous hydrocarbons during the injecting
the steam stream; and [0324] (iii) producing the mobilized viscous
hydrocarbons during both the injecting the heated solvent vapor
stream and the injecting the steam stream.
[0325] Embodiment 61: The method of any one of embodiments 1-60,
wherein the method further includes draining the mobilized viscous
hydrocarbons, under the influence of gravity, at least one of:
[0326] (i) toward a lower region of the heated chamber that
includes the at least substantially horizontal region of the
production well; and [0327] (ii) toward the at least substantially
horizontal region of the production well.
[0328] Embodiment 62: The method of any one of embodiments 1-61,
wherein the at least substantially horizontal region of the
injection well and the at least substantially horizontal region of
the production well define an average separation distance
therebetween.
[0329] Embodiment 63: The method of embodiment 62, wherein the
average separation distance is at least one of: [0330] (i) at least
1 meter; [0331] (ii) at least 2 meters; [0332] (iii) at least 3
meters; [0333] (iv) at least 4 meters; [0334] (v) at least 5
meters; [0335] (vi) at most 10 meters; [0336] (vii) at most 8
meters; [0337] (viii) at most 6 meters; [0338] (ix) at most 5
meters; [0339] (x) at most 4 meters; [0340] (xi) at most 3 meters;
and [0341] (xii) at most 2 meters.
[0342] Embodiment 64: The method of any one of embodiments 1-63,
wherein the method further includes at least one of: [0343] (i)
forming the injection well; and [0344] (ii) forming the production
well.
[0345] Embodiment 65: A method for recovering viscous hydrocarbons
from a subterranean formation, the method comprising: [0346]
injecting, via an at least substantially horizontal region of an
injection well, a heated solvent vapor stream into a heated chamber
that extends within the subterranean formation; [0347] fluidly
contacting the viscous hydrocarbons with the heated solvent vapor
stream and condensing the heated solvent vapor stream to generate
mobilized viscous hydrocarbons within the heated chamber and to
form a chamber liquid that includes condensed solvent and the
mobilized viscous hydrocarbons; [0348] accumulating the chamber
liquid to form a chamber liquid pool within the heated chamber and
to immerse the at least substantially horizontal region of the
injection well within the chamber liquid pool; [0349] subsequent to
the accumulating, injecting, via the at least substantially
horizontal region of the injection well, a steam stream into the
heated chamber such that the steam stream directly contacts at
least a region of the chamber liquid pool and vaporizes a fraction
of the chamber liquid from the chamber liquid pool; [0350] during
at least one of the injecting the heated solvent vapor stream, the
fluidly contacting, and the injecting the steam stream, producing
at least a portion of the chamber liquid, as a produced chamber
liquid, from the subterranean formation via an at least
substantially horizontal region of a production well that extends
within the heated chamber and below the at least substantially
horizontal region of the injection well; and [0351] sequentially
repeating, for a plurality of injection cycles, the injecting the
heated solvent vapor steam, the fluidly contacting, the injecting
the steam stream, and the producing.
[0352] Embodiment 66: The method of embodiment 65, wherein the
sequentially repeating, for a plurality of injection cycles,
includes the accumulating.
[0353] Embodiment 67: The method of embodiment 65 in combination
with any suitable step of any of the methods of any of claims
1-64.
INDUSTRIAL APPLICABILITY
[0354] The methods disclosed herein are applicable to the oil and
gas industries.
[0355] It is believed that the disclosure set forth above
encompasses multiple distinct inventions with independent utility.
While each of these inventions has been disclosed in its preferred
form, the specific embodiments thereof as disclosed and illustrated
herein are not to be considered in a limiting sense as numerous
variations are possible. The subject matter of the inventions
includes all novel and non-obvious combinations and subcombinations
of the various elements, features, functions and/or properties
disclosed herein. Similarly, where the claims recite "a" or "a
first" element or the equivalent thereof, such claims should be
understood to include incorporation of one or more such elements,
neither requiring nor excluding two or more such elements.
[0356] It is believed that the following claims particularly point
out certain combinations and subcombinations that are directed to
one of the disclosed inventions and are novel and non-obvious.
Inventions embodied in other combinations and subcombinations of
features, functions, elements and/or properties may be claimed
through amendment of the present claims or presentation of new
claims in this or a related application. Such amended or new
claims, whether they are directed to a different invention or
directed to the same invention, whether different, broader,
narrower, or equal in scope to the original claims, are also
regarded as included within the subject matter of the inventions of
the present disclosure.
* * * * *